How to go about uploading a mod?

I’ve more or less finished a “alpha” version of a mod i’m working to replace world generation with submerged dessert buildings, however I’m a bit confused as to the process of how to upload a file. I’ve checked over the modding guide for github and its a bit confusing, as this is the first time I’m using a filesharing website, especially to upload instead of download things.
What exactly do I need to do to upload a “working” mod to a site?

If you’re uploading it to github. All you need is to create a repository and put your files in there.